The invention relates to a heating or air conditioning system for the interior of a motor vehicle, of the type having an exchangeable air filter comprising two mutually adjoining filter sections, surrounded peripherally by a holding frame. For the insertion of the filter, the first filter section is initially fed in through an assigned opening and is then displaced sidewards into its working position and the second filter section is only then inserted into the cleared receiving chamber.
A filter which can be inserted in this way and which can be removed again in the reverse order for exchange purposes is described in German Patent Document DE 40 04 501 C2 corresponding to U.S. Pat. No. 5,062,353. In this arrangement the filter admission opening is disposed on the back of a glove box. Due to the lack of accessibility, however, a check cannot be made to ensure that the filter sections, in the course of their insertion procedure, reach the pre-determined working position, so that a reduction in the efficiency of the filter as a result of leaks cannot be completely ruled out.
An object of the invention is to provide a filter-receiving system in which the filter sections, during their insertion, are guaranteed to be transferred into their pre-determined working position, which position prevents any leakage-air from passing through.
This object is achieved according to preferred embodiments of the invention by providing an air filter assembly comprising:
a filter holding frame having a filter exchange opening and filter section guide devices for guiding insertion movement of filter sections in to respective in-use positions in the holding frame,
and first and second filter sections configured to be inserted into the holding frame with the first filter section inserted into the exchange opening and then laterally displaced to its in-use position followed by the second filter section being inserted into the exchange opening with mutual overlapping interengagement of facing lateral edges of the first and second filter sections to thereby reliably hold the first and second filter sections together in their respective in-use positions.
In the course of being fitted, the first filter section is transferred during the laterally directed displacement movement into a working position which no longer is changed uncontrolledly upon the insertion of the second filter section. Because the holding frame in preferred embodiments is provided with at least two holding-down devices which resiliently engage over the narrow sides of the first filter section and exhibit, in the transverse-displacement direction of the first filter section, a bulged profile in the direction of the latter. Thus the insertion movement of the filter sections is reliably controlled in a simple matter.
In a further aspect of preferred embodiments of the invention, the holding frame is equipped, on its side assigned to the rear, narrow side of the second filter section in the feed-in direction of the latter, with a holding-down device resiliently engaging over the narrow side, which holding down device exhibits, in addition to butt slopes for the narrow side sliding therebelow, a bulged profile in the direction of the latter, so that, one after the other, both filter sections easily reach the position envisaged for them in interaction with the guide devices in the area of their assigned narrow sides.
When the holding frame is provided on the feed-in the filter sections with a hinged holding-down device which, when swivelled upwards, resiliently engages over the assigned narrow side of the inserted second filter section and simultaneously locks onto the edge of the holding frame in a detachable fashion, then, on the one hand, the filters can be easily exchanged and, on the other hand, the inserted second filter section can be easily fixed in place on the feed-in side.